Host-induced increase in larval sea bass mortality in a gnotobiotic challenge test with Vibrio anguillarum (original) (raw)
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Journal of Fish Diseases, 2012
The location and cell damage caused by Vibrio anguillarum, the causative agent of classical vibriosis, within the developing gut of the newly hatched sea bass, Dicentrarchus labrax (L.), is unknown. A gnotobiotic sea bass model was used to investigate the early interactions of V. anguillarum with sea bass larvae. In the present study, germ-free sea bass larvae were orally exposed to a V. anguillarum HI-610 pathogen labelled with the green fluorescent protein (GFP-HI-610) and sampled at regular intervals. Pathogenic colonization of gut enterocytes was observed 2 h post-exposure (p.e.) and onwards, whereas bacteria within the swim bladder were visualized 48 h p.e and onwards. Ultrastructural findings demonstrated direct bacterial contact with the host cell in the oesophageal mucosa and putative attachment to microvilli of mid-and hindgut enterocytes. The present findings form a starting point for studies assessing the impact of potential candidates (probiotics, prebiotics, antimicrobial peptides) to mitigate bacterial virulence.
Veterinary microbiology, 2015
In this study, we investigated the impact of the host factors mucin, bile salts and cholesterol on the virulence of the economically important aquatic pathogen Vibrio anguillarum towards sea bass larvae. Pretreatment of V. anguillarum with either one of the host factors (at 10 mg l(-1)) prior to inoculation into the sea bass rearing water increased virulence of the bacterium, although the effect of cholesterol was not significant. Each of the three host factors significantly increased several virulence-related phenotypes in V. anguillarum, i.e. protease activity, flagellar motility, biofilm formation and exopolysaccharide production, whereas there was no effect on growth of the bacterium under these conditions. Furthermore, the host factors increased the expression of genes involved in these phenotypes, i.e. the metalloprotease empA, the flagellar transcriptional regulator fleQ, the flagellin gene flaA, the chemotaxis methyltransferase gene cheR, the exopolysaccharide biosynthesis g...
Diseases of Aquatic Organisms, 1995
A Vibrio anguillarum-related (VAR) strain, isolated in pure culture from an epizootic in a commercial hatchery producing Argopecten purpuratus, was characterized, and its potential pathogenicity to veliger larvae of A. purpuratus determined. Experimental challenges indicated that the bacterium affects larval survival at concentrations of 104 to 108 cells ml-l The effect of water quality and temperature on pathogenicity was also evaluated. Larval survival in seawater filtered through 5 pm pore-size membranes was 45.6%, whereas using seawater passed through 1 and 0.2 pm filters, larval survival increased to 66.4 and 80.4 % respectively. Temperature also affected pathogenicity as larval survival at 15OC for 24 h was 69.3 % but decreased to 30 and 26.9 % at 20 and 25°C respectively. Toxic activity was found in cell-free supernatant of bacterial culture. Larval survival was reduced to 68.9 and 36.4% after 20 and 40% (v/v) of supernatant, respectively, was added to the rearing water. These results suggest that exotoxins produced by the VAR strain play an in~portant role in its pathogenicity for scallop larvae.
Veterinarski arhiv
Vibrioses caused by different members of the genus Vibrio are common diseases in aquaculture characterised by systemic infections, high mortalities, and economic losses of fish and shellfish. Farming of European sea bass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) has rapidly grown over the last decade in Croatia but its economic efficacy is significantly jeopardized by losses due to Vibrio anguillarum and Vibrio harveyi infection. Therefore, we studied and compared the most prominent similarities and differences in the environmental conditions, clinical signs and conventional and molecular diagnostic methods of vibriosis caused by both bacterial pathogens. Outbreaks in sea bass and sea bream caused by V. anguillarum mostly occur during the spring and autumn, following a fast increase or decrease in the sea temperature, whereas infections with V. harveyi occur during the summer months at a temperature above 20o C. They have a similar clinical appearance in the acute...
Asian Fisheries …, 2004
Hatchery produced Asian sea bass Lates calcarifer (Bloch) juveniles (120 days post hatch) maintained in a fish hatchery, Central Institute of Brackishwater Aquaculture (CIBA), were used in the present study. Diseased and moribund fish showed haemorrhages at the bases of dorsal, pectoral and anal fins. The affected fish stopped taking food. Bacteria isolated from the aseptic kidney samples drawn from the moribund fish belonged to the genus Vibrio as evidenced through selective growth on TCBS agar. Colony morphology, growth and the biochemical characteristics suggested that the bacterium was Vibrio anguillarum-like (VAL). This VAL bacterium, injected at varying doses in Liza macrolepis and Oreochromis mossambicus revealed LD 50 end points of 10 4.17 and 10 5.47 CFU, respectively. Exposure of L. calcarifer juveniles to graded levels of virulent bacterium via injection and bath showed that a cell density of 10 4.5 CFU/fish and 10 6.3 CFU per ml, respectively, can kill half of the exposed population. Investigations carried out on the histopathology of the infected fish indicated severe necrotic degenerative changes in the gills with mild to extensive lamellar fusion and hyperplasia of naturally infected seabass juveniles, while that of the experimentally infected fish showed no discernible changes. Natural infection showed wide spread chronic histopathological manifestations while, the experimental infection accounted for acute phase pathogenesis -related manifestations. reported to have accounted for £11 million . Vibrio spp was responsible for a phenomenal 67.8% of the bacterial diseases of gilt-head seabream, collected from south-western Spain during 1990. Vibriosis is a serious problem in farmed seabass (L. calcarifer) in Singapore (Cheong et al. 1983), Thailand (Chinabut and and Australia (Glazebrook and Campbell 1986). First success in India, of induced maturation and breeding of the Asian seabass was achieved by the Central Institute of Brackishwater Aquaculture in 1997. Since then, the species has attracted much attention of the coastal aquaculturists in India. Identification of potential pathogens of farmed seabass is of immense importance. Isolation, identification, characterization, virulence and histopathology of infection of Vibrio spp. isolated from farm produced Asian seabass (L. calcarifer) are discussed in this paper. Tilapia and mullet are among the important brackishwater species as forage and food fish. Hence, susceptibility of these species to varying doses of exposure to VAL bacterium was tested and histopathologies of experimental and natural infection in L. calcarifer are discussed in the present paper.
Intellectual Property Rights: Open Access, 2016
The intensive cultivation conditions for marine shellfish larvae may easily cause microbial problems. Vibrio species are commonly present in disease affected shrimp farms, seawater and sediments. Vibriosis has resulted in severe economic losses to aquaculture worldwide and affects many farm-raised fishes, shrimps, crustaceans and Artemia. V. harveyi and closely related bacterial species are commonly found in estuarine and coastal marine habitats and can readily be isolated from different environmental sources. The lethal toxicity of extracellular products (ECPs) produced by V. harveyi V. anguillarum and V. parahaemolyticus isolated from shrimp and Artemia culture. Also the virulence factors such as protease, proteolytic activity, and phospholipase and lipase activity and haemolytic activity was studied the virulence strains compared with the non-virulent Vibrio strains. This paper addresses the virulence and epidemiology of vibrio pathogen; pathogenesis of its disease.
Vibrio anguillarum serovars associated with vibriosis in fish
Journal of Fish Diseases, 1994
A total ol" 317 Vibrio anguillantm strains isolated from diseased fish together with 14 V. anguillarum serogroup O2 and V. ordalii type strains were serotyped using the European scrotyping system. Marked speeies difterenees were reeorded. In isolates from belonged to other serogroups or were non-typeablc. Figures for turbot were similar to those from salmonids. In 32 isolates from sea bass, sea bream and mullet, most strains belonged to serogroup Ol. while one was O2a. one O7, and the rest non-typcable In cod sero\ar O2 was dominant while only a minor proportion belonged to other serogroups or were non-typeable. The eel isolates belonged equally to serovars O2 and O3. All O2 strains were subtyped with absorbed O2a and O2b antisera. O2a was dominant in all fish speeies. but in eod. the relative number of O2b isolates was eonsiderably higher than in other fish speeies.
Diseases of Aquatic Organisms, 1998
The pathogen~city of Vibrio alginolyticus on Haliotls rufescens veliger larvae and 4 d old postlarvae was tested in small-scale static bioassays with different bacterial concentrations (10' to 106 cells ml-l). Larval and postlarval survival were evaluated at 24 and 48 h. Results suggest that V alginolyticus can cause massive mortality in larvae of H. rufescens within 24 h at concentrations above 105 cell ml-', while a concentration of 10%ell ml-' is required to produce the same effect in abalone postlarvae. The potential application of these results to hatchery conditions is discussed.
Characterization of vibriophages and their interactions with the fish pathogen Vibrio anguillarum
Applied and Environmental Microbiology, 2014
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